Which of the following is an example of a ferrous metal?

Steel is a primary example of a ferrous metal because it is primarily composed of iron, which is the defining characteristic of ferrous metals. The term "ferrous" itself is derived from the Latin word "ferrum," meaning iron. Ferrous metals are known for their magnetic properties and resistance to oxidation, although they can be susceptible to rust when exposed to moisture unless they are alloyed with other elements.

In contrast, aluminum and brass are classified as non-ferrous metals. Aluminum is lightweight and resistant to corrosion, while brass is an alloy of copper and zinc. Plastic is not a metal at all and is a polymer-based material, highlighting the diversity of materials but cementing steel's place as a quintessential example of a ferrous metal.